Questions: Which one of the following correctly ranks the compounds in order of lowest boiling point to highest boiling point based only in intermolecular forces? A CH3CH2OH<CH3OCH3<CH3CH2CH3 B CH3OCH3<CH3CH2CH3<CH3CH2OH C CH3CH2CH3<CH3CH2OH<CH3OCH3 D CH3CH2CH3<CH3OCH3<CH3CH2OH

Solution Steps

To determine the boiling points, we need to consider the types of intermolecular forces present in each compound:

• \(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{OH}\) (ethanol) has hydrogen bonding, dipole-dipole interactions, and London dispersion forces.
• \(\mathrm{CH}_{3} \mathrm{OCH}_{3}\) (dimethyl ether) has dipole-dipole interactions and London dispersion forces.
• \(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{3}\) (propane) has only London dispersion forces.

The strength of intermolecular forces from weakest to strongest is:

1. London dispersion forces
2. Dipole-dipole interactions
3. Hydrogen bonding

• Propane (\(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{3}\)) has the weakest intermolecular forces (London dispersion forces only), so it will have the lowest boiling point.
• Dimethyl ether (\(\mathrm{CH}_{3} \mathrm{OCH}_{3}\)) has dipole-dipole interactions and London dispersion forces, so it will have a higher boiling point than propane but lower than ethanol.
• Ethanol (\(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{OH}\)) has hydrogen bonding, which is the strongest intermolecular force among the three, so it will have the highest boiling point.

Based on the analysis, the correct order from lowest boiling point to highest boiling point is: \[ \mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{3}<\mathrm{CH}_{3} \mathrm{OCH}_{3}<\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{OH} \]

Final Answer